Automatic tension release for blind stitch sewing machines



y 7, 1940- c. w. MUELLER AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MACHINES 6 Sheets-Sheet 1 Filed Sept. 22, 1937 Char/es l4. Mue//er WSQ.WZZW

May 7, 1940. c. w. MUELLER AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MACHINES Filed Sept. 22, 1937 6 Sheets-Sheet 2 Cha r/es' W Muefler' May 7, 1940 w MUELLER 2,199,751

AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MACHINES Filed Sept. 22, 1937 6 Sheets-Sheet 3 Char/es W Mlle/k2 May 7, 1940. c. w. MUELLER AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MACHINES Filed Sept. 22, 1937 6 Sheets-Sheet 4 W N s nH @Um fflwfiliiiilll- L. I m .mm mm W i Q Q G 1/, N .w w m? Q 1 Q Q R Q Q .MW H F N NQQ W\-- NW Q% Q 1 H- IMWRH Q Nu Wm I Saw R mm. k m k 677?: r/es WMUel/er HINES May 7, 1940. c. w. MUELLER AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MAC Filed Sept. 22, 19s? 6 Sheet5-Sheei 5 Char/es W Moe/lei y 7, 1940- c. w. MUELLER 2.199.751

AIJTOMATIC TENSION-RELEASE FOR BLIND STITCH SEWING MACHINES Filed Sept. 22, 1937 6 Sheets-Sheet 6- N m) I v v lllllllllllllllllllllllllll Char/es (Mae/Aer Patented May 7, 1940 UNITED STATES PATENT OFFICE AUTOMATIC TENSION RELEASE FOR BLIND STITCH SEWING MACHINES Application September 22,1937, Serial No. 165,204

17 Claims.

provements in sewing machines generally, although more particularly to improvements in means for releasing the needle thread tension 1-: employed in sewing machines of the blind stitch type, and is directed to improvements over prior Patent 2,064,881, issued to Louis G. Bowman December 22, 1936.

The principal object of the invention is to provide a needle thread tension release mechanism which is housed within the sewing machine frame.

Another object of the invention is to provide such a'tension' release mechanism which is operable upon depression of a work support whereby the stitched fabric may be readily withdrawn from the machine.

With these and other objects in view which will more fully appear, the nature of the in- 2Q) vention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure l is a top plan View of a blind stitch sewing machine embodying my invention,

Figure 2 is a right hand elevation thereof, Figure 3 is a partial bottom plan View of the machine,

Figure 4 is a'vertical section taken through the machine,

Figure 5 is an enlarged partial top plan View of the frame arm and showing particularly the train of tension releasing mechanism extending therealong,

Figure 6 is a vertical section taken through the arm and'standard,

Figure '7' is an enlarged section showing the thread tension discs and the associated releas ing means, and

Figure 8 is a view showing the construction of Figure '7 in separated perspectives.

Like reference numerals designate corresponding parts throughout the several figures of the drawings. The sewing machine includes a main frame which comprises a base 5, a hollow standard 6, a hollow arm I which extends laterally from the upper end of. the standard and terminates in a 1 forwardly extending hollow arm 8 which is inclined downwardly and forwardly relative to the base, and a post 9 which is integral with the base and is located at the front thereof and at the right of the arm 8, the post being inclined forwardly and having its upper portion disposed in This invention relates to new and useful ima vertical plane located in front of the front or slot formed therein, the foot being forwardly and downwardly inclined in a plane disposed in parallelism to the major axis of said arm 8.

Journaled in the upper end of the standard 6 and in the arm i is a main shaft l0, and jour-- naled in the arm 8 and extending longitudinally;

thereof is an oscillatory needle shaft l I having a needle arm l2 fixed toits front end. The needle shaft H is journaled in bushings l3, I4 mounted in front and rear bearing lugs l5, l6 which are integral with the arm 8, the rear end of the front bushing l3 projecting rearwardly beyond its bearing lug IS. The needle shaft H is located directly above the presser foot opening and has its longitudinal axis in a downwardly and forwardly inclined plane disposed in parallelism with the presser foot. Attached to the needle arm I2 is a curved needle I! which reciprocates across the opening of the foot. The needle shaft II is oscillated from the main shaft l0 preferably by connections such as is shown in my prior Patent 2,018,186, October 22, 1935. A looper or spread l8 cooperates with the needle I1 in the usual manner to form single thread chain stitches, although any other type of complemental stitch forming mechanism may be employed if desired.

A work support 0 is clamped to a horizontal pivot shaft I9 journaled'in bearings formed in the post 8 of the main frame. It will be noted that the pivot shaft I9 is disposed in a plane parallel to the main shaft Ill and that said pivot shaft is located considerably in front of the needle I! as well as in front of the presser foot B.

Operating in the presser foot opening for intermittently projecting a node of fabric upwardly into needle penetrating position, is a ridge forming element D which in this instance consists of a disc fixed to an oscillatory operating shaft journaled at its ends in bearing lugs depending from the under side of the work support C. The operating shaft 20 is disposed in a horizontal plane in parallelism not only with the main shaft Ill but also with the pivot shaft IQ of the work support. It will, therefore, be seen that the work support C extends rearwardly from the pivot shaft l9 to a point under the presser foot B and that this work support is capable of swinging downwardly away from the presser foot or upwardly toward the same. It will also be observed that the shaft 20 which operates the ridge forming element D, is disposed in rear of the pivot shaft l9 and is movable upwardly and downwardly with the work support and consequently when the work support is lowered the ridge forming element D will be correspondingly lowered with respect to the path of the needle.

The operating shaft 20 is oscillated preferably from the main shaft H] by a train of mechanism shown in my prior Patent 2,018,186, referred to above.

The work support C is yieldably held against depression by a strong coil spring 2! which is located within the base 5, the spring being connected at its forward end to a bracket arm 22 which is rigidly connected to and depends from the front edge of the work support, the connection between the bracket and the work support being located in front of the pivot shaft IS. The rear end of the spring is anchored to the base 5 through the medium of a screw 23 which has threadable engagement in the base. It will, therefore, be apparent that the spring 2| functions to normally urge the work support C and the ridge-forming element D in an upward direction, i. e., toward the needle path. It is, there- I fore, necessary to provide a stop for limiting the 30 upward movement of the work support and the ridge forming element, otherwise the element would be projected across the path of the needle. It is also desirable to provide a stop for this purpose which is adjustable whereby the ini- 35 tial setting of the ridge-forming element relative to the needle path may be readily accomplished. To this end, a horizontal shaft 24 is journaled in the base 5 and has its longitudinal axis disposed in parallelism with the pivot shaft is of the work support. Fixed to one end of this shaft 24 is a rock arm 25 having a cam periphery 26. The free end of the bracket arm 22 is normally held in yieldable contact with the cam periphery 25 of said rock arm 25 by the coil spring 3|. It will, therefore, be apparent that the rock arm 25 constitutes an adjustable stop for limiting the upward movement of the work support C together with the ridge-forming element D. Manually operable means E is provided for rocking the stop arm 25 to either raise the work support and the ridge-forming element positively against the tension of the coil spring 2| or to permit the lowering thereof by the action of said spring, and thereby initially adjust the vertical position of the disc D with respect to the path of needle travel.

When it is desired to insert a fabric into the machine preparatory to the seaming thereof, or to withdraw the seamed fabric from the machine, the work support is depressed a sufficient distance below the presser foot. For this purpose, a knee-press lever 27 is provided. This lever is removably secured to one end of a horizontal rock'shaft 28 which is journaled in the base 5 and has its longitudinal axis disposed in a plane at right angles to the pivot shaft [9 of the work support. A rock arm 29 is fixed to the shaft 28 and is connected by a link 30 to the work support C at a point in rear of said pivot shaft 19. Thus upon movement of the knee-press lever 2'! to the right, the work support C will be swung downwardly against the tension of the coil spring 2! and away from the presser foot 33, and the bracket arm 22 will be moved forwardly away from the stop 25. Upon release of the knee-press lever the spring 2| will return the work support to its initial position with the bracket arm 22 against the stop 25.

Formed in the forwardly extending frame arm 8 adjacent its free end and directly above the needle shaft H, is an opening 3|. Mounted in said opening is the base 32 of a tension post 33, a set screw 34 being mounted in. the arm for cooperation with said base 32 to removably secure the same in said opening. The post 33 is provided with a slot 35 which extends upwardly throughout its length from said base and forms resultant spring arms which are exteriorly threaded to receive a tensioning nut 36. A superposed pair of needle thread tension discs 31, 38 which are provided with concentric openings, are freely mounted for independent vertical movements on the post 33, the lower disc 38 being seated on the base 32 of the post. A tension plate 39 is mounted on the post directly above the discs 31, 38, the plate being provided with spaced openings 49, 4! to receive the spring arms of the post and forming a resultant intermediate bridge 42 which lies between said spring arms. A coil spring 43 which is disposed around the post between the nut '36 and the tension plate 39, functions to tension the needle thread T which passes between the discs.

The base 32 is provided at its upper end with an axial bore 46 which is in open communication with the lower end of the slot 35 of the post 33, and at its lower end with an axial counter bore 45 which is in open communication with the bore 34. A tension release pin 46 which is slidably mounted in the counter bore 45 is provided at its upper end with an integral reduced portion 4? which is slidably mounted in the bore 44, the upper end of the portion 41 projecting upwardly into the slot 35 of the post 33 and being normally disposed below and in contact with the bridge 42 of the tension plate 39, the lower rounded end of the pin 46 projecting below the base 32 of the post.

Located on the right hand side of the needle shaft H and extending longitudinally of the frame arm 8 is a rock shaft 48 which is journaled in the lugs l5, 16 of said arm. Fixed to this rock shaft by a screw 49 is a rock arm or lever 55 which projects laterally over the needle shaft H and below the tension release pin 46. The upper end of the rock arm 50 is pros vided with a longitudinal groove 5| for receiving the lower rounded end of the pin 46. It will be seen that the spring 43 maintains the bridge 42 in contact with the upper end of the pin 46. It will also be observed that when the rock shaft 48 is rocked in a clockwise direction, the rock arm 5!} will elevate the pin 46 and the tension plate 39 thereby freeing the needle thread T from the tension of said spring. This rock shaft 48 is actuated from the manually operable rock shaft 28 through the medium of a train of mechanism which is housed within the standard 6 and arms i and 8. To this end, the rock shaft 48 is provided with an actuating rock arm 52 which is pivotally connected bya link 53 which extends longitudinally within the frame arm I. The left end of the link passes through an opening 54 which is conjointly formed in the arms 1 and 8 and the right hand end of said link projects into the upper end of the standard 6. A bell crank lever 55 is located at the juncture of the standard 6 and the arm I and is fulcrumed as at 56 within the standard. This bell crank lever 55 includes a downwardly extending vertical arm end of the link'53 passes freely through an opening 59 formed in the vertical arm 51 and a stop 60' is mounted on the projecting end of the link for longitudinal set adjustments by means of a set screw 6!. A vertically disposed link 62 is located within the standard 6 and has its upper end 'pivotally connected to the horizontal arm 58 of the bell crank lever 55 and its lower end pivotally connected to a rock arm 63 fixed on the rock shaft 28. Preferably the link 62 is provided intermediate its ends with a coil spring 64 to form a yieldable connection between the bell crank arm 53 and the rock arm 63. v

The tension release lever 50 is provided'with a laterally extending and integral stop arm '55 which prevents said lever from contacting the needle shaft ll.

It will therefore be observed that when the knee-press lever 21' is moved to the, right, the

needle thread tension will be released and the work support C will be depressed; that the ten sion will be released prior to the worksupport being fully depressed, and that by reason of the 'yieldablelink 64 the knee-press lever may be moved farther in the same direction to effect the complete depression of the work support.

It is of course to'be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

' I claim:

1. In 'a sewing machine, the combination with a frame including a hollow standard and a laterally extending hollow arm, of a stitch forming mechanism mountedon the free end of said arm' and including a reciprocatory threaded needle, releasable needle thread tensioning means mounted on said arm, and manually operable means extending along and housed within the standard and the arm for releasing said tensioning means. Y

2. In a sewing machine, the combination with a frame including a hollow standard and 'alater'ally 'extendinghollow arm, of astitch forming mechanism mounted on the free end of said arm and including a reciprocatory threaded needle, releasable needle thread tensioning means mounted on 'said arm, and manually operable means extending along and housed within the standard and the arm for releasing said tension ing means, said means including a bell crank lever fulcrumed in the frame at the juncture of the standard and the arm.

3. In a sewing machine, the combination with a frame including a standard and a laterally extending arm, of a stitch forming mechanism;

mounted on the free end of said arm and including a reciprocatory threaded needle, releasable needle thread tensioning means mounted on said arm, a manuallyoperable rock shaft journ'aled in the frame below the standard, and operating connections between the tensioning means and the shaft and disposed wholly within the frame for releasing said tensioning means upon actuation of said shaft. 4. In a sewing machine, the combination with a frame including a standard and an arm extending laterally from the upper end thereof, of a stitch forming mechanism mounted on said arm and including a reciprocatory threaded needle, a releasable needle thread tensioning means mounted on said arm, and means for releasing said tensioning means comprising a release lever mounted on the arm in cooperative tween the standard and the arm, a link connection between the release lever and one arm of the bell crank lever, and a manually operable shaft journaled on the frame below the bell crank lever and having operable connection with the other arm thereof.

5. In a sewing machine, the combination with a frame including a hollow standard and a hollow arm extending laterally from the upper end thereof, of a stitch forming mechanism mounted relation to said tensioning means, a 'bell crank" lever fulcrumed on the frame at the. juncture beon said arm and including a reciprocatory threaded needle, a releasable needle thread tensioning means mounted on said arm, and means for releasing said tensioning means comprising a release lever mounted in the arm'in cooperative relation to said tensioning means, a bell crank lever fulcrumed in the frame at the juncture between the standard and the arm, a link connection extending within the arm between the release lever and one arm of the bell crank lever, and a manually operable shaft jcurnaled in the frame below the bell crank lever and having operable connection with the other arm thereof, said connection extending within the standard. I

6. In a sewing machine, the combination with a frame including a standard and an arm extending laterally from the upper end thereof, of a stitch forming mechanism mounted on said arm and including a 'reciprocatory threaded needle, a releasable needle thread tensioning means mounted on said arm, and means for releasing said tensioning means comprising .a release lever mounted on the arm in cooperative relation to said tensioning means, a bell crank lever fulcrumed on the frame at the'juncture between the standard and the arm, a link connection between the release'lever and one arm of the bell crank lever,- a manually operable shaft journaled on the frame below the bell crank lever, and a link connection between said manually operable shaft and the other arm of said bell crank lever, one of said links being longitudinally yieldable.

7'. In a sewing machine, the combination with a frame including a standard, and an arm extending laterally from, the upper end thereof, of a stitch forming mechanism mounted on said arm and including a needleshaft and a reciprocatory threaded needle, a tension post having a base mounted on said arm, said post being provided with a longitudinal slot forming spring'arms, a pair of needle thread tension discs freely mounted on said post directly above the basethereof, a tension plate having spaced openings for receiving the spring arms of the post and provided with a bridge located between said arms, a tensioning nut threadably mounted on the post, a coil spring disposed around the post between the nut and the tension plate, a tension release pin slidably mounted in the base of said post and having its upper end located directly below and in contact with the bridge of the tension plate, and means for releasing the tension on said discs comprising a release lever mounted on the frame arm for elevating said pin, and manually operable means extending along the frame arm and standard for actuating said release lever,

8. In a sewing machine, the combination with a frame including a hollow standard, and a hollow arm extending laterally from the upper end thereof, of a stitch forming mechanism mounted on said arm and including a needle shaft and a reciprocatory threaded needle, 'a tension post 75g having a base mounted in said frame arm, said post being provided with a longitudinal slot forming spring arms, a pair of needle thread tension discs freely mounted on said post directly above the base thereof, a tension plate having spaced openings for receiving the spring arms of the post and provided with a bridge located between said arms, a tensioning nut threadably mounted on the post, a coil spring disposed around the post between the nut and the tension plate, a tension release pin slidably mounted in the base of said post and having its upper end located directly below and in contact with the bridge of the tension plate, and means for releasing the tension on said discs comprising a release lever mounted in the frame arm for elevating said pin, a bell cranklever located within the frame atcthe juncture between the frame arm and the standard and fulcrumed on the latter, a link connection between the release lever and one arm of the bell crank lever, and a manually operable shaft journaled in the frame below the bell crank lever and having operable connection with the other arm thereof.

9. In a sewing machine, the combination with a frame including a hollow standard and a hollow arm extending laterally from the upper end thereof, the latter being provided with spaced bearings, of a stitch forming mechanism mounted on said forwardly extending arm and including a needle shaft and a reciprocatory threaded needle, a tension post having a base mounted on said forwardly extending arm, said post being provided with a longitudinal slot forming spring arms, a pair of needle thread tension discs freely mounted on said post directly above the base thereof, a tension plate having spaced openings for receiving the spring arms of the post and provided with a bridge located between said arms,

a tensioning nut threadably mounted on the post,

a coil spring disposed around the post between the nut and the tension plate, a tension release pin slidably mounted in the base of said post and having its upper end located directly below and in contact with the bridge of the tension plate, and means for releasing the tension on said discs comprising a rock shaft located within the frame arm at one side of the needle shaft and journaled in the spaced bearings thereof, a release lever fixed to said rock shaft and projecting laterally between the tension release pin and said needle shaft, a rock arm fixed to said rock shaft, a bell crank lever located within the frame at the juncture between the frame arm and the standard and fulcrumed on the latter, said bell crank lever including a horizontal arm and a depending vertical arm, a link extending longitudinaliy within the frame arm and having pivotal connection at one end with said rock arm, the other end of said link projecting freely through the vertical arm of the bell crank lever, a stop mounted on the projecting end of the link for adjustments therealong, an actuating rock shaft journaled in the frame below the bell crank lever, a rock arm fixed to said actuating shaft, and a link connecting the horizontal arm of the bell crank lever with the rock arm of the actuating shaft.

10. In a sewing machine, the combination with a frame including a base, a hollow standard, and a hollow arm extending laterally from the upper end thereof and terminating in a forwardly extending arm, of a stitch forming mechanism mounted on said forwardly extending arm and including a needle shaft and a reciprocatory threaded needle, said forwardly extending arm having spaced bearings in which the needle shaft is journaled, a tension post having a base mounted on said forwardly extending arm, said post being provided with a longitudinal slot forming spring arms, a pair of needle thread tension discs freely mounted on said post directly above the base thereof, a tension plate having spaced openings for receiving the spring arms of the post and provided with a bridge located between said arms, a tensioning nut threadably mounted on the post, a coil spring disposed around the post between the nut and the tension plate, a tension release pin slidably mounted in the base of said post and having its upper end located directly below and in contact with the bridge of the tension plate, and means for releasing the tension on said discs comprising a rock shaft located within the forwardly extending arm at one side of the needle shaft and journaled in the spaced lugs of said arm, an actuating lever fixed to said rock shaft and projecting laterally between the tension release pin and said needle shaft, a stop arm rigidly connected to said lever and overhanging the end of the adjacent needle shaft bearing and normally dis-,

posed above and in spaced relation thereto, a rock arm fixed to said rock shaft, a bell crank lever located within the frame at the juncture between the frame arm and the standard and fulcrumed on the latter, said bell crank lever including a horizontal arm and a depending vertical arm, a link extending longitudinally within the lateral frame arm and having pivotal connections with said rock arm and with the vertical arm of the bell crank lever, an actuating rock shaft journaled in the base below the bell crank lever, and a link connection between said manually operable shaft and the horizontal arm of the bell crank lever, one of said links being longitudinally yieldable. 1

11. In a blind stitch sewing machine, the combination with a frame including a hollow standard and a laterally extending hollow arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a work support mounted on the frame to move downwardly and having a portion disposed under the foot, releasable needle thread tensioning means mounted on the frame arm, a manually operable rock shaft journaled in the frame, operating connections between the tension means and the shaft and extending within the standard and the frame-arm for releasing said tension means, and connections between said shaft and the work support for depressing the latter.

12. In a blind stitch sewing machine, the combination with a frame including a hollow standard and a laterally extending hollow arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a work support mounted on the frame to move downwardly and having a portion disposed under the foot, releasable needle thread tensioning means mounted on the frame arm, a manually operable rock shaft journaled in the frame, operating connections between the tension means and the shaft and extending within the standard and the frame arm for releasing said tension means, said connections including a bell crank lever fulcrumed in the frame at the juncture of the standard and the frame arm, and

connections between said shaft and the work support for depressing the latter.

13. In a blind stitch sewing machine, the combination with a frame including a standard and a laterally extending arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a work support mounted on the frame to move downwardly and having a portion disposed under the foot, releasable needle thread tensioning means mounted on the frame arm, and means for releasing said tensioning means and for depressing the work support comprising a manually operable shaft journaled in the frame, a bell crank lever fulcrumed on the frame at the juncture of the standard and the frame arm, a. release lever mounted on the frame arm in cooperative relation to said tension means, a link connection between one arm of the bell crank lever and said release lever, a link connection between the other arm of said bell crank lever and said shaft, and an operative connection between said shaft and said work support.

14. In a blind stitch sewing machine, the combination with a frame including a standard and a laterally extending arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a work support mounted on the frame to move downwardly and having a portion disposed under the foot, releasable needle thread tensioning means mounted on the frame arm, and means for releasing said tensioning means and for depressing the work support comprising a manually operable shaft journaled in the frame, a bell crank lever fulcrumed on the frame at the juncture of the standard and the frame arm, a release lever mounted on the frame arm in cooperative relation to said tension means, a link connection between one arm ,of the bell crank lever and said release lever, a yieldable link connection between the other arm of said bell crank lever and said shaft, and an operative connection between said shaft and said work support.

15. In a blind stitch sewing machine, the combination with a frame including a. hollow standard and a laterally extending hollow arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory in the standard-and the frame arm for releasing said tension means, and connections between said shaft and the work support for depressing the latter.

16. In a blind stitch sewing machine, the combination with a frame including a standard and a laterally extending'arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a work support pivoted on the frame to swing downwardly and having a portion disposed under said foot, releasable needle thread tensioning means mounted on the frame arm, and means for releasing said tensioning means and for depressing the work support comprising a manually operable shaft journaled in the frame, a bell crank lever fulcrumed on the frame at the juncture of the standard and the frame arm, a release lever mounted on the frame arm in cooperative relation to said tension means, a link connection between one arm of the bell crank lever and said release lever, a link connection between the other arm of said bell crank lever and said shaft, and an operative connection between said shaft and said work support.

17. In a blind stitch sewing machine, the combination with a frame including a standard and a laterally extending-arm, of a horizontal presser foot rigidly secured to said arm, a stitch forming mechanism located above the presser foot and including a reciprocatory threaded needle, a depressible work support mounted on the frame and having a portion disposed under the foot, releasable needle thread tensioning means mounted on the frame arm, and a single manually operable element having force-transmitting connections with the work support and independent force transmitting connections with the thread tensioning means whereby said element may be manipulated for depressing said work support and for releasing said thread tensioning means prior to the full depression of said work support.

CHARLES W. MUELLER. 

